Caption: Tick. Light micrograph of the head of a male castor bean tick (Ixodes ricinus) showing its mouthparts (yellow). The mouthparts of a tick consist of three visible components. The two outer jointed parts are highly mobile palps. Between the palps, at centre, is a rod-shaped structure, the hypostome. The palps do not enter the skin of the host while the tick is feeding, while the hypostome is inserted into the host's skin. The backward-pointing projections prevent easy removal of the tick. Magnification: x120 when printed at 10 centimetres across.